This is a note to let you know that I've just added the patch titled
x86/perf: Fix CR4.PCE propagation to use active_mm instead of mm
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-perf-fix-cr4.pce-propagation-to-use-active_mm-instead-of-mm.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 5dc855d44c2ad960a86f593c60461f1ae1566b6d Mon Sep 17 00:00:00 2001
From: Andy Lutomirski <luto@xxxxxxxxxx>
Date: Thu, 16 Mar 2017 12:59:39 -0700
Subject: x86/perf: Fix CR4.PCE propagation to use active_mm instead of mm
From: Andy Lutomirski <luto@xxxxxxxxxx>
commit 5dc855d44c2ad960a86f593c60461f1ae1566b6d upstream.
If one thread mmaps a perf event while another thread in the same mm
is in some context where active_mm != mm (which can happen in the
scheduler, for example), refresh_pce() would write the wrong value
to CR4.PCE. This broke some PAPI tests.
Reported-and-tested-by: Vince Weaver <vincent.weaver@xxxxxxxxx>
Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Borislav Petkov <bpetkov@xxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 7911d3f7af14 ("perf/x86: Only allow rdpmc if a perf_event is mapped")
Link: http://lkml.kernel.org/r/0c5b38a76ea50e405f9abe07a13dfaef87c173a1.1489694270.git.luto@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/cpu/perf_event.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -1996,8 +1996,8 @@ static int x86_pmu_event_init(struct per
static void refresh_pce(void *ignored)
{
- if (current->mm)
- load_mm_cr4(current->mm);
+ if (current->active_mm)
+ load_mm_cr4(current->active_mm);
}
static void x86_pmu_event_mapped(struct perf_event *event)
Patches currently in stable-queue which might be from luto@xxxxxxxxxx are
queue-4.4/x86-perf-fix-cr4.pce-propagation-to-use-active_mm-instead-of-mm.patch